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200-420: Loran-C is a hyperbolic radio navigation system that allows a receiver to determine its position by listening to low frequency radio signals that are transmitted by fixed land-based radio beacons . Loran-C combined two different techniques to provide a signal that was both long-range and highly accurate, features that had been incompatible. Its disadvantage was the expense of the equipment needed to interpret

400-408: A nautical chart at those angles, producing an intersection that reveals the ship's location. Radio methods can also use the same concept with the aid of a radio direction finder , but due to the nature of radio propagation, such instruments are subject to significant errors, especially at night. More accurate radio navigation can be made using pulse timing or phase comparison techniques, which rely on

600-520: A 14-month circumnavigation of the world. Ordered by President Theodore Roosevelt , it was a mission designed to demonstrate the Navy's capability to extend to the global theater. By 1911, the U.S. had begun building the super-dreadnoughts at a pace to eventually become competitive with Britain. The 1911 also saw the first naval aircraft with the navy which would lead to the informal establishment of United States Naval Flying Corps to protect shore bases. It

800-405: A 3 MHz design. Extensive signal-strength measurements were made by mounting a conventional radio receiver in a station wagon and driving around the eastern states. However, the custom receiver design and its associated cathode-ray tube displays proved to be a bigger problem. In spite of several efforts to design around the problem, instability in the display prevented accurate measurements as

1000-469: A blip on the display in the same fashion as a target on the radar, and the exact delay between the primary and secondary easily determined. Consider the same examples as our original absolute-timed cases. If the receiver is located on the midpoint of the baseline the two signals will be received at exactly the same time, so the delay between them will be zero. However, the delay will be zero not only if they are located 150 km from both stations and thus in

1200-647: A change in their rating from their previous rating (i.e., MMCM) to CMDCM. The stars for Command Master Chief are silver, while stars for Fleet, and gold stars for Force. Additionally, CMCs wear a badge, worn on their left breast pocket, denoting their title (Command/Fleet/Force). Insignia and badges of the United States Navy are military "badges" issued by the Department of the Navy to naval service members who achieve certain qualifications and accomplishments while serving on both active and reserve duty in

1400-433: A clock of the required accuracy was difficult enough to build in fixed form, let alone portable. A high-quality crystal oscillator , for instance, drifts about 1 to 2 seconds in a month, or 1.4 × 10  seconds per hour . This may sound small, but as light travels 300 million metres per second (190,000 miles per second), this represents a drift of 420 km each hour. Only a few hours of flight time would render such

1600-520: A competing system known as Navarho. Around this period the United States Navy began work on a similar system using combined pulse and phase comparison, but based on the existing LORAN frequency of 200 kHz. By this time the United States Navy had handed operational control of the LORAN system to the Coast Guard, and it was assumed the same arrangement would be true for any new system as well. Thus,

1800-402: A complete set of 8 stations in 1983. Omega would also prove to be one of the shortest-lived systems, shutting down on 20 September 1997. Omega stations broadcast a continuous-wave signal in a specific time-slot. The atomic clocks also ensured that their signals were sent out with the right frequency and phase; unlike previous systems, Omega did not need to have a primary/secondary arrangement as

2000-446: A conventional radio receiver hooked to an oscilloscope. Because a secondary could not instantaneously transmit its signal pulse on receipt of the primary signal, a fixed delay was built into the signal. No matter what delay is selected, there will be some locations where the signal from two secondary would be received at the same time, and thus make them difficult to see on the display. Some method of identifying one secondary from another

2200-466: A development effort known as Project 3 that was similar to Gee. Only halting progress had been made by the time they were introduced to Gee, which was already entering production. Gee was immediately selected for the 8th Air Force and the Project 3 team turned their attention to other uses, eventually considering convoy navigation in particular. The new concept relied on the use of skywaves to allow

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2400-466: A fixed 45° phase shift to every pulse, so simple continuous-wave jamming signals could be identified and rejected. The Cytac system underwent an enormous series of tests across the United States and offshore. Given the potential accuracy of the system, even minor changes to the groundwave synchronization were found to cause errors that could be eliminated — issues such as the number of rivers

2600-403: A formidable force in the years prior to World War II , with battleship production being restarted in 1937, commencing with USS  North Carolina  (BB-55) . Though ultimately unsuccessful, Japan tried to neutralize this strategic threat with the surprise attack on Pearl Harbor on 7 December 1941. Following American entry into the war , the U.S. Navy grew tremendously as the United States

2800-651: A frequent actor in American foreign and military policy. The United States Navy is part of the Department of the Navy , alongside the United States Marine Corps , which is its coequal sister service. The Department of the Navy is headed by the civilian secretary of the Navy . The Department of the Navy is itself a military department of the Department of Defense , which is headed by the secretary of defense . The chief of naval operations (CNO)

3000-472: A hyperbolic curve centred on the baseline. Navigational charts can be drawn with the curves for selected delays, say every 0.1 ms. The operator can then determine which of these lines they lie on by measuring the delay and looking at the chart. A single measurement reveals a range of possible locations, not a single fix. The solution to this problem is to simply add another secondary station at some other location. In this case two delays will be measured, one

3200-616: A large number of unique signals for widespread coverage. The Decca Navigation System was originally developed in the US, but eventually deployed by the Decca Radio company in the UK and commonly referred to as a British system. Initially developed for the Royal Navy as an accurate adjunct to naval versions of Gee, Decca was first used on 5 June 1944 to guide minesweepers in preparation for

3400-514: A line in Krasnodar, Revda and Novosibirsk, the later being the primary station. In 1991 two additional stations came online at Khabarovsk and Seyda. The stations use frequencies between 11 and 14 kHz. Two complicating factors for satnav systems are: (1) the transmitter stations (satellites) are moving; and (2) GPS satellite transmissions are synchronized with UTC (with a published offset), thus providing precise time. Item (1) necessitates that

3600-642: A major effect on naval planning is the Pivot to East Asia . In response, the Secretary of the Navy Ray Mabus stated in 2015 that 60 percent of the total U.S. fleet will be deployed to the Pacific by 2020. The Navy's most recent 30-year shipbuilding plan, published in 2016, calls for a future fleet of 350 ships to meet the challenges of an increasingly competitive international environment. A provision of

3800-433: A meeting of the U.S. Army's Microwave Committee. The Army Air Corps were interested in the concept for aircraft navigation, and after some discussion they returned a requirement for a system offering accuracy of about 1 mile (1.6 km) at a range of 200 miles (320 km), and a maximum range as great as 500 miles (800 km) for high-flying aircraft. The Microwave Committee, by this time organized into what would become

4000-635: A national navy was debated in the Second Continental Congress . Supporters argued that a navy would protect shipping, defend the coast, and make it easier to seek support from foreign countries. Detractors countered that challenging the British Royal Navy , then the world's preeminent naval power, was a foolish undertaking. Commander in Chief George Washington resolved the debate when he commissioned

4200-430: A navigational chart. The curves are known as lines of position or LOP. In practice, radio navigation systems normally use a chain of three or four stations, all synchronized to a master signal that is broadcast from one of the stations. The others, the secondaries , are positioned so their LOPs cross at acute angles, which increases the accuracy of the fix. So for instance, a given chain might have four stations with

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4400-502: A navy able to reform those enemies to mankind or crush them into non-existence. Naval power . . . is the natural defense of the United States. The Navy was rooted in the colonial seafaring tradition, which produced a large community of sailors, captains, and shipbuilders. In the early stages of the American Revolutionary War , Massachusetts had its own Massachusetts Naval Militia . The rationale for establishing

4600-643: A number of unique capabilities, including Military Sealift Command , Naval Expeditionary Combat Command , and Naval Information Forces . The United States Navy has seven active numbered fleets – Second , Third , Fifth , Sixth , Seventh and Tenth Fleets are each led by a vice admiral , and the Fourth Fleet is led by a rear admiral . These seven fleets are further grouped under Fleet Forces Command (the former Atlantic Fleet), Pacific Fleet, Naval Forces Europe-Africa, and Naval Forces Central Command, whose commander also doubles as Commander Fifth Fleet;

4800-402: A portable receiver located on the midpoint of the line drawn between the two stations, known as the baseline . In this case, the signals will, necessarily, take 0.5 ms to reach the receiver. By measuring this time, they could determine that they are precisely 150 km from both stations, and thereby exactly determine their location. If the receiver moves to another location along the line,

5000-413: A positioning and navigation Loran service, with the result that the UK announced its trial eLoran service would be discontinued from the same date. In conventional navigation, measuring one's location, or taking a fix , is accomplished by taking two measurements against well known locations. In optical systems this is typically accomplished by measuring the angle to two landmarks, and then drawing lines on

5200-867: A quarter of whom are in ready reserve. Of those on active duty, more than eighty percent are enlisted sailors and around fifteen percent are commissioned officers ; the rest are midshipmen of the United States Naval Academy and midshipmen of the Naval Reserve Officer Training Corps at over 180 universities around the country and officer candidates at the Navy's Officer Candidate School . Enlisted sailors complete basic military training at boot camp and then are sent to complete training for their individual careers . Sailors prove they have mastered skills and deserve responsibilities by completing Personnel Qualification Standards (PQS) tasks and examinations. Among

5400-465: A senior non-commissioned officer in the other services, and must have a minimum 14 years in service. Sailors in pay grades E-1 through E-3 are considered to be in apprenticeships. They are divided into five definable groups, with colored group rate marks designating the group to which they belong: Seaman, Fireman, Airman, Constructionman, and Hospitalman. E-4 to E-6 are non-commissioned officers (NCOs), and are specifically called Petty officers in

5600-497: A service member may choose to further their career by becoming a Command Master Chief Petty Officer (CMC). A CMC is considered to be the senior-most enlisted service member within a command, and is the special assistant to the Commanding Officer in all matters pertaining to the health, welfare, job satisfaction, morale, use, advancement and training of the command's enlisted personnel. CMCs can be Command level (within

5800-408: A short pulse at a specific frequency. One of these stations, called the "secondary" is also equipped with a radio receiver . When this receiver hears the signal from the other station, referred to as the "primary", it triggers its own broadcast. The primary station can then broadcast any series of pulses, with the secondary hearing these and generating the same series after a 1 ms delay. Consider

6000-526: A significant effect on pulse timing, but much less so for phase changes. Decca thus found itself in great demand for helicopter use, where runway approach aids like ILS and VOR were not suitable for the small airfields and essentially random locations the aircraft were used. One serious disadvantage to Decca was that it was susceptible to noise, especially from lightning . This was not a serious concern for ships, who could afford to wait out storms, but made it unsuitable for long-range air navigation where time

6200-449: A single frequency would work just as well, given the right electronics. This was especially good news, as the 200 kHz frequency was interfering with existing broadcasts, and had to be moved to 160 kHz during testing. Through this period the issue of radio spectrum use was becoming a major concern, and had led to international efforts to decide on a frequency band suitable for long-range navigation. This process eventually settled on

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6400-404: A single unit, such as a ship or shore station), Fleet level (squadrons consisting of multiple operational units, headed by a flag officer or commodore), or Force level (consisting of a separate community within the Navy, such as Subsurface, Air, Reserves). CMC insignia are similar to the insignia for Master Chief, except that the rating symbol is replaced by an inverted five-point star, reflecting

6600-442: A system for sending additional data. At about the same time, Motorola proposed a new system using pseudo-random pulse-chains. This mechanism ensures that no two chains within a given period (on the order of many seconds) will have the same pattern, making it easy to determine if the signal is a groundwave from a recent transmission or a multi-hop signal from a previous one. The system, Multi-User Tactical Navigation Systems (MUTNS)

6800-406: A system unusable, a situation that remained in force until the introduction of commercial atomic clocks in the 1960s. However, it is possible to accurately measure the difference between two signals. Much of the development of suitable equipment had been carried out between 1935 and 1938 as part of the efforts to deploy radar systems. The UK , in particular, had invested considerable effort in

7000-428: A third measurement is needed to determine the exact location. Hyperbolic location systems were first used during World War I in acoustic location systems for locating enemy artillery . The sound of a shell being fired was received by several microphones, and the time of reception sent to a computing center to plot the location. These systems were used into World War II . The first hyperbolic radio navigation system

7200-460: A time. The switch from A to C was extremely rapid, due largely to rapidly falling prices which led to many users' first receiver being Loran-C. By the late 1970s the Coast Guard decided to turn off Loran-A, in favour of adding additional Loran-C stations to cover gaps is its coverage. The original Loran-A network was shut down in 1979 and 1980, with a few units used in the Pacific for some time. Given

7400-463: A uniform group repetition interval (GRI) defined in microseconds . The amount of time before transmitting the next set of pulses is defined by the distance between the start of transmission of primary to the next start of transmission of primary signal. Hyperbolic navigation Such systems rely on the ability of two widely separated stations to broadcast a signal that is highly correlated in time. Typical systems broadcast either short pulses at

7600-456: A very specific and stable part of the rising edge of the pulse, and this zero-crossing was used to trigger a very short-time sampling gate. This system replaced the complex system of clocks used in CYCLAN. By simply measuring the time between the zero-crossings of the master and secondary, pulse-timing was extracted. The output of the envelope sampler was also sent to a phase-shifter that adjusted

7800-721: Is a distinct, separate service branch with its own uniformed service chief – the Commandant of the Marine Corps, a four-star general. The Marine Corps depends on the Navy for medical support (dentists, doctors , nurses, medical technicians known as corpsmen ) and religious support (chaplains). Thus, Navy officers and enlisted sailors fulfill these roles. When attached to Marine Corps units deployed to an operational environment they generally wear Marine camouflage uniforms, but otherwise, they wear Navy dress uniforms unless they opt to conform to Marine Corps grooming standards. In

8000-431: Is based on the difference in times (or phase) instead of the absolute time. The basic idea is that it is relatively easy to synchronize two ground stations, using a signal shared over a phone line for instance, so one can be sure that the signals received were sent at exactly the same time. They will not be received at exactly the same time, however, as the receiver will receive the signal from the closer station first. Timing

8200-729: Is immediately under and reports to the Secretary of the Navy. At the same time, the Chief of Naval Operations is a member of the Joint Chiefs of Staff , which is the second-highest deliberative body of the armed forces after the United States National Security Council , although it plays only an advisory role to the President and does not nominally form part of the chain of command . The Secretary of

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8400-509: Is needed to reduce this ambiguity. LORAN-C achieved this by sending unique details in the pulses so each station could be uniquely identified. The signal was started off when the primary broadcast a sequence of nine pulses, with the precise timing between each pulse being used to identify the station. Each of the Secondary stations then sent out its own signals, consisting of eight pulses in similar identifying patterns. The receivers could use

8600-569: Is the Soviet Union 's counterpart to LORAN-C, and operates on similar principles and the same frequency. It differs primarily in details of the pulse envelopes. There are five CHAYKA chains distributed around the former Soviet Union, each with a primary and between two and four secondaries. Alpha, more correctly known by its Soviet name, RSDN-20, is essentially a version of Omega deployed in the former Soviet Union starting in 1962. The initial system used only three transmitters running roughly in

8800-420: Is the most senior Navy officer serving in the Department of the Navy. To recruit, train, equip, and organize to deliver combat ready Naval forces to win conflicts and wars while maintaining security and deterrence through sustained forward presence. The U.S. Navy is a seaborne branch of the military of the United States . The Navy's three primary areas of responsibility: U.S. Navy training manuals state that

9000-596: The 1966 Palomares B-52 crash incident and the subsequent search for missing hydrogen bombs, and Task Force 71 of the Seventh Fleet's operation in search for Korean Air Lines Flight 007 , shot down by the Soviets on 1 September 1983. The U.S. Navy continues to be a major support to U.S. interests in the 21st century. Since the end of the Cold War, it has shifted its focus from preparations for large-scale war with

9200-662: The American Civil War , in which the Union had a distinct advantage over the Confederacy on the seas. A Union blockade on all major ports shut down exports and the coastal trade, but blockade runners provided a thin lifeline. The Brown-water navy components of the U.S. navy control of the river systems made internal travel difficult for Confederates and easy for the Union. The war saw ironclad warships in combat for

9400-655: The Battle of Okinawa . By 1943, the navy's size was larger than the combined fleets of all the other combatant nations in World War II. By war's end in 1945, the U.S. Navy had added hundreds of new ships, including 18 aircraft carriers and 8 battleships, and had over 70% of the world's total numbers and total tonnage of naval vessels of 1,000 tons or greater. At its peak, the U.S. Navy was operating 6,768 ships on V-J Day in August 1945. Doctrine had significantly shifted by

9600-900: The Bureau of Naval Personnel , the Office of Naval Research , the Office of Naval Intelligence , the United States Naval Academy , the Naval Safety Command , the Naval Aviation Warfighting Development Center , and the United States Naval Observatory . Official Navy websites list the Office of the Chief of Naval Operations and the Chief of Naval Operations as part of the shore establishment, but these two entities effectively sit superior to

9800-759: The Continental Navy ) The United States Navy ( USN ) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States . It is the world's most powerful navy and the largest by tonnage, at 4.5 million tons in 2021 and in 2009 an estimated battle fleet tonnage that exceeded the next 13 navies combined. It has the world's largest aircraft carrier fleet, with 11 in service , one undergoing trials, two new carriers under construction, and six other carriers planned as of 2024. With 336,978 personnel on active duty and 101,583 in

10000-466: The D-Day invasions. The system was developed post-war and competed with GEE and other systems for civilian use. A variety of reasons, notably its ease-of-use, kept it in widespread use into the 1990s, with a total 42 chains around the world. A number of stations were updated in the 1990s, but the widespread use of GPS led to Decca being turned off at midnight on 31 March 2000. Decca was based on comparing

10200-608: The Decca Navigator System . The former requires sharp pulses of signal, and their accuracy is generally limited to how rapidly the pulses can be turned on and off, which is a function of the carrier frequency . There is an ambiguity in the signal; the same measurements can be valid at two locations relative to the broadcasters, but in normal operation, they are hundreds of kilometres apart, so one possibility can be eliminated. The second system uses constant signals ("continuous wave") and takes measurements by comparing

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10400-726: The Department of Homeland Security . Per a subsequent announcement, the US Coast Guard, in accordance with the DHS Appropriations Act, terminated the transmission of all U.S. Loran-C signals on 8 February 2010. On 1 August 2010 the U.S. transmission of the Russian American signal was terminated, and on 3 August 2010 all Canadian signals were shut down by the USCG and the CCG. The European Union had decided that

10600-543: The Global Positioning System (GPS) in the 1990s. In 2023 a prototype navigation system was tested based on detection of muon subatomic particles coming with cosmic rays , which would work underground and underwater. Consider two ground-based radio stations located at a set distance from each other, say 300 km so that they are nearly exactly 1 ms apart at light speed . Both stations are equipped with identical transmitters set to broadcast

10800-541: The MIT Radiation Laboratory , took up development as Project 3 . During the initial meetings, a member of the UK liaison team, Taffy Bowen , mentioned that he was aware the British were also working on a similar concept, but had no information on its performance. The development team, led by Loomis, made rapid progress on the transmitter design and tested several systems during 1940 before settling on

11000-547: The Ready Reserve , the U.S. Navy is the third largest of the United States military service branches in terms of personnel. It has 299 deployable combat vessels and about 4,012 operational aircraft as of July 18, 2023. The United States Navy traces its origins to the Continental Navy , which was established during the American Revolutionary War and was effectively disbanded as a separate entity shortly thereafter. After suffering significant loss of goods and personnel at

11200-682: The USCGC Androscoggin starting in April 1956. Meanwhile, Loran-B proved to have serious problems keeping their transmitters in phase, and that work was abandoned. Minor changes were made to the Cytac systems to further simplify it, including a reduction in the pulse-chain spacing from 1200 to 1000 μs, the pulse rate changed to 20  pps to match the existing Loran-A system, and the phase-shifting between pulses to an alternating 0, 180-degree shift instead of 45 degrees at every pulse within

11400-740: The United States Army Air Forces were moving towards smaller crews, only three in the Boeing B-47 Stratojet for instance, a high degree of automation was desired. Two contracts were accepted; Sperry Gyroscope proposed the CYCLAN system (CYCLe matching LorAN) which was broadly similar to LF LORAN but with additional automation, and Sylvania proposed Whyn using continuous wave navigation like Decca, but with additional coding using frequency modulation . In spite of great efforts, Whyn could never be made to work, and

11600-439: The limited duty officer (LDO) in the Navy. Warrant officers perform duties that are directly related to their previous enlisted service and specialized training. This allows the Navy to capitalize on the experience of warrant officers without having to frequently transition them to other duty assignments for advancement. Most Navy warrant officers are accessed from the chief petty officer pay grades, E-7 through E-9, analogous to

11800-617: The permafrost was much shorter than expected and synchronization of the signals between the stations using ground waves proved impossible. The tests also showed that the system was extremely difficult to use in practice; it was easy for the operator to select the wrong sections of the waveforms on their display, leading to significant real-world inaccuracy. In 1946 the Rome Air Development Center sent out contracts for longer-ranged and more-accurate navigation systems that would be used for long-range bombing navigation. As

12000-490: The 1950s. A PLL produces a steady output signal with the same frequency and phase as an input signal, even if that input is periodic or poorly received. In this case the important feature was that the PLL allowed the re-construction of a continuous signal from a number of short pulses. A system using PLLs could receive a single pulsed signal, like Gee, and then re-construct a continuous tone for phase measurement, like Decca. Re-using

12200-433: The 1980s and 90s, this process repeated itself, but this time the military was able to separate GPS's signals in such a way that it could provide both secure military and insecure civilian signals at the same time. GPS was more difficult to receive and decode, but by the 1990s the required electronics were already as small and inexpensive as Loran-C, leading to rapid adoption that has become largely universal. Although Loran-C

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12400-509: The 1990s led to a rapid drop-off in Loran-C use. Discussions about the future of Loran-C began in the 1990s; several turn-off dates were announced and then cancelled. In 2010, the US and Canadian systems were shut down, along with Loran-C/CHAYKA stations that were shared with Russia. Several other chains remained active; some were upgraded for continued use. At the end of 2015, navigation chains in most of Europe were turned off. In December 2015 in

12600-418: The 2018 National Defense Authorization Act called for expanding the naval fleet to 355 ships "as soon as practicable", but did not establish additional funding nor a timeline. The U.S. Navy falls under the administration of the Department of the Navy , under civilian leadership of the Secretary of the Navy (SECNAV). The most senior naval officer is the Chief of Naval Operations (CNO), a four-star admiral who

12800-554: The AN/SPN-31, the first widely used Loran-C receiver. The AN/SPN-31 weighed over 100 pounds (45 kg) and had 52 controls. Airborne units followed, and an adapted AN/SPN-31 was tested in an Avro Vulcan in 1963. By the mid-1960s, units with some transistorization were becoming more common, and a chain was set up in Vietnam to support the United States' war efforts there. A number of commercial airline operators experimented with

13000-563: The Barbary pirates, blockaded the Barbary ports and executed attacks against the Barbary' fleets. The U.S. Navy saw substantial action in the War of 1812 , where it was victorious in eleven single-ship duels with the Royal Navy. It proved victorious in the Battle of Lake Erie and prevented the region from becoming a threat to American operations in the area. The result was a major victory for

13200-475: The CYCLAN system gave all involved the confidence that these could be met. The resulting system was known as Cytac. To solve the complexity problem, a new circuit was developed to properly time the sampling of the signal. This consisted of a circuit to extract the envelope of the pulse, another to extract the derivative of the envelope, and finally another that subtracted the derivative from the envelope. The result of this final operation would become negative during

13400-534: The Chief of Naval Operations, Admiral Elmo Zumwalt , authorized the Navy to celebrate its birthday on 13 October to honor the establishment of the Continental Navy in 1775. The United States was without a navy for nearly a decade, a state of affairs that exposed U.S. maritime merchant ships to a series of attacks by the Barbary pirates . The sole armed maritime presence between 1790 and the launching of

13600-503: The Coast Guard may be called upon to operate as a service within the Navy. At other times, Coast Guard Port Security Units are sent overseas to guard the security of ports and other assets. The Coast Guard also jointly staffs the Navy's naval coastal warfare groups and squadrons (the latter of which were known as harbor defense commands until late-2004), which oversee defense efforts in foreign littoral combat and inshore areas. The United States Navy has over 400,000 personnel, approximately

13800-592: The Cyclan transmitters, the US Navy started experiments with such a system in the mid-1950s, and turned the system on permanently in 1957. Numerous chains followed, eventually providing around-the-world coverage near US allies and assets. Although less accurate that Decca, it offered the combination of reasonable accuracy and long ranges, a combination that obsoleted almost all other systems then in use and led to their gradual withdrawal. LORAN-C remained in service well into

14000-470: The Decca phase-comparison system. He imagined a system specifically for medium-accuracy global navigation, and thus selected the extremely low frequency of 10 kHz as the basis for the signal. However, the problem with phase ambiguity, as in the case of Decca, meant that the system was not practical at the time. The primary problem was synchronizing the stations. Gee and LORAN stations were close enough that

14200-505: The Decca-like Cyclan and Navarho concepts. None of those proved to offer any real advance over Decca; they either offered marginally improved range, or better range but too little accuracy to be useful. Gee and LORAN-A became possible due to the development of the oscilloscope – before this the accurate measurement of time was not possible. LORAN-C became possible due to the development of the low-cost phase-locked loop (PLL) in

14400-546: The Mediterranean in 1957. Further chains covering the North Atlantic and large areas of the Pacific followed. At the time global charts were printed with shaded sections representing the area where a 3-mile (4.8 km) accurate fix could be obtained under most operational conditions. Loran-C operated in the 90 to 110 kHz frequency range. Loran-C had originally been designed to be highly automated, allowing

14600-677: The Mediterranean, where it participated in the Second Barbary War that ended piracy in the region, South America, Africa, and the Pacific. From 1819 to the outbreak of the Civil War, the Africa Squadron operated to suppress the slave trade , seizing 36 slave ships, although its contribution was smaller than that of the much larger British Royal Navy. After 1840 several secretaries of the navy were southerners who advocated for strengthening southern naval defenses, expanding

14800-734: The Navy and Chief of Naval Operations are responsible for organizing, recruiting, training, and equipping the Navy so that it is ready for operation under the commanders of the unified combatant commands . There are nine components in the operating forces of the U.S. Navy: the United States Fleet Forces Command (formerly United States Atlantic Fleet), United States Pacific Fleet , United States Naval Forces Central Command , United States Naval Forces Europe , Naval Network Warfare Command , Navy Reserve , United States Naval Special Warfare Command , and Operational Test and Evaluation Force . Fleet Forces Command controls

15000-461: The Navy reactivated the Fourth Fleet to control operations in the area controlled by Southern Command, which consists of US assets in and around Central and South America. Other number fleets were activated during World War II and later deactivated, renumbered, or merged. Shore establishments exist to support the mission of the fleet through the use of facilities on land. Among the commands of

15200-424: The Navy. Petty Officers perform not only the duties of their specific career field but also serve as leaders to junior enlisted personnel. E-7 to E-9 are still considered Petty Officers, but are considered a separate community within the Navy. They have separate berthing and dining facilities (where feasible), wear separate uniforms, and perform separate duties. After attaining the rate of Master Chief Petty Officer,

15400-487: The Project 3 team told the Army Air Force to adopt Gee, and instead, at the behest of the British team, realigned their efforts to provide long-range navigation on the oceans where Gee was not useful. This led to United States Navy interest, and a series of experiments quickly demonstrated that systems using the basic Gee concept, but operating at a lower frequency around 2 MHz would offer reasonable accuracy on

15600-723: The Soviet Union to special operations and strike missions in regional conflicts. The navy participated in Operation Enduring Freedom , Operation Iraqi Freedom , and is a major participant in the ongoing War on Terror , largely in this capacity. Development continues on new ships and weapons, including the Gerald R. Ford -class aircraft carrier and the Littoral combat ship . Because of its size, weapons technology, and ability to project force far from U.S. shores,

15800-700: The U.S. Army at the Niagara Frontier of the war, and the defeat of the Native American allies of the British at the Battle of the Thames . Despite this, the U.S. Navy could not prevent the British from blockading its ports and landing troops. But after the War of 1812 ended in 1815, the U.S. Navy primarily focused its attention on protecting American shipping assets, sending squadrons to the Caribbean,

16000-469: The U.S. Navy and its decisive victory over the outdated Spanish Navy in 1898 brought a new respect for American technical quality. Rapid building of at first pre-dreadnoughts, then dreadnoughts brought the U.S. in line with the navies of countries such as Britain and Germany. In 1907, most of the Navy's battleships, with several support vessels, dubbed the Great White Fleet , were showcased in

16200-614: The U.S. Navy's first warships in 1797 was the U.S. Revenue-Marine , the primary predecessor of the U.S. Coast Guard . Although the United States Revenue Cutter Service conducted operations against the pirates, the pirates' depredations far outstripped its abilities and Congress passed the Naval Act of 1794 that established a permanent standing navy on 27 March 1794. The Naval Act ordered the construction and manning of six frigates and, by October 1797,

16400-401: The U.S. economy and quality of life. This new strategy charts a course for the Navy, Coast Guard, and Marine Corps to work collectively with each other and international partners to prevent these crises from occurring or reacting quickly should one occur to prevent negative impacts on the U.S. In 2010, Admiral Gary Roughead, Chief of Naval Operations, noted that demands on the Navy have grown as

16600-549: The United States Coast Guard was given the choice of naming the systems, and decided to rename the existing system Loran-A, and the new system Loran-B. With Cytac fully developed and its test system on the east coast of the United States mothballed, the United States Navy also decided to re-commission Cytac for tests in the long-range role. An extensive series of tests across the Atlantic were carried out by

16800-525: The United States Navy grew under an ambitious ship building program associated with the Naval Act of 1916 . Naval construction, especially of battleships, was limited by the Washington Naval Conference of 1921–22, the first arms control conference in history. The aircraft carriers USS  Saratoga  (CV-3) and USS  Lexington  (CV-2) were built on the hulls of partially built battle cruisers that had been canceled by

17000-445: The United States, there was also renewed discussion of funding an eLoran system, and NIST offered to fund development of a microchip-sized eLoran receiver for distribution of timing signals. The National Timing Resilience and Security Act of 2017, proposed resurrecting Loran as a backup for the United States in case of a GPS outage caused by space weather or attack. The original LORAN was proposed in 1940 by Alfred Lee Loomis at

17200-432: The ambiguities in Decca. The same rapid development of microelectronics that made Loran-A so easy to operate worked equally well on the Loran-C signals, and the obvious desire to have a long-range system that could also provide enough accuracy for lake and harbour navigation led to the "opening" of the Loran-C system to public use in 1974. Civilian receivers quickly followed, and dual-system A/C receivers were also common for

17400-440: The ambiguity in the fine measurement. To provide an extra-fine guidance signal, Loran-D interleaved another train of eight pulses immediately after the signals from one of the existing Loran-C stations, folding the two signals together. This technique became known as "Supernumary Interpulse Modulation" (SIM). These were broadcast from low-power portable transmitters, offering relatively short-range service of high accuracy. Loran-D

17600-488: The atmosphere, offers more resilience to these issues. There has been considerable debate about the relative merits of keeping the Loran-C system operational as a result of such considerations. In November 2009, the United States Coast Guard announced that Loran-C was not needed by the U.S. for maritime navigation. This decision left the fate of LORAN and eLoran in the United States to the Secretary of

17800-455: The band from 90 to 100 kHz. CYCLAN appeared to suggest that accuracy at even lower frequencies was not a problem, and the only real concern was the expense of the equipment involved. The success of the CYCLAN system led to a further contract with Sperry in 1952 for a new system with the twin goals of working in the 100 kHz range while being equally accurate, less complex and less expensive. These goals would normally be contradictory, but

18000-473: The basic system. Another advantage is that it is easy to display the relative phase of two signals using simple electromechanical gauges. In contrast to Gee and LORAN, which required the use of oscilloscopes to measure the signal timings, Decca used a series of three mechanical pointers which were a fraction of the cost, took up less room, and allowed simultaneous examination of three signals. This made Decca both much less expensive and easier to use. Decca had

18200-619: The burden of retaliating against the Japanese on the small number of aircraft carriers. During World War II some 4,000,000 Americans served in the United States Navy. The potential for armed conflict with the Soviet Union during the Cold War pushed the U.S. Navy to continue its technological advancement by developing new weapons systems, ships, and aircraft. U.S. naval strategy changed to that of forward deployment in support of U.S. allies with an emphasis on carrier battle groups. The navy

18400-490: The capture of California with large-scale land operations coordinated with the local militia organized in the California Battalion . The Navy conducted the U.S. military's first large-scale amphibious joint operation by successfully landing 12,000 army troops with their equipment in one day at Veracruz , Mexico. When larger guns were needed to bombard Veracruz, Navy volunteers landed large guns and manned them in

18600-463: The chain. The result was Loran-C. Testing of the new system was intensive, and over-water flights around Bermuda demonstrated that 50% of fixes lay within a circle of 260 ft (79 m) radius, a dramatic improvement over the original Loran-A, meeting the accuracy of the Gee system, but at much greater range. The first chain was set up using the original experimental Cytac system, and a second one in

18800-405: The chance to do so until much later. Similar concepts were also used in the experimental Navarho system in the United States. It was known from the start of the LORAN project that the same CRT displays that showed the LORAN pulses could, when suitably magnified, also show the individual waves of the intermediate frequency . This meant that pulse-matching could be used to get a rough fix, and then

19000-554: The clocks were accurate enough to trigger the signals without an external reference. To start the sequence, the station in Norway would initially broadcast on 10.2 kHz for 0.9 seconds, then turned off for 0.2 seconds, then broadcast on 13.6 kHz for 1.0 seconds, repeating this pattern. Each station broadcast a series of four such signals lasting about a second each, and then stood silent while other stations took their turn. At any given instant, three stations would be broadcasting at

19200-411: The current U.S. Navy remains an asset for the United States. Moreover, it is the principal means through which the U.S. maintains international global order, namely by safeguarding global trade and protecting allied nations. In 2007, the U.S. Navy joined with the U.S. Marine Corps and U.S. Coast Guard to adopt a new maritime strategy called A Cooperative Strategy for 21st Century Seapower that raises

19400-426: The current dial reading allowed the navigator to directly read the current delay and look it up on a chart, a far easier process than Gee or LORAN. It was so much easier to use that Decca later added an automatic charting feature that formed a moving map display . Later additions to the signal chain allowed the zone and lane to be calculated directly, eliminating the need for manually setting the lane counters and making

19600-509: The development of their Chain Home system. The radar display systems for Chain Home were based on oscilloscopes (or oscillographs as they were known at time) triggered to start their sweep when the broadcast signal was sent. Return signals were amplified and sent into the display, producing a "blip". By measuring the distance along the face of the oscilloscope of any blips, the time between broadcast and reception could be measured, thus revealing

19800-403: The difference between the primary and secondary "A", and the other between the primary and secondary "B". By looking up both delay curves on the chart, two intersections will be found, and one of these can be selected as the likely location of the receiver. This is a similar determination as in the case with direct timing/distance measurements, but the hyperbolic system consists of nothing more than

20000-424: The difference between two signals can be easily accomplished, first by physically measuring them on a cathode-ray tube, or simple electronics in the case of phase comparison. The difference in signal timing does not reveal the location by itself. Instead, it determines a series of locations where that timing is possible. For instance, if the two stations are 300 km apart and the receiver measures no difference in

20200-427: The display until they could see the varying signal within the blips, and then use phase comparison to accurately line up the timing. At low frequencies and long ranges, it would be difficult to know whether you are looking at the current phase of the signals directly from the stations, or comparing one direct signal to one from a cycle ago, or perhaps one reflected off the ionosphere . Some form of secondary information

20400-426: The display. To distinguish the chains in these cases, a second "A" signal, the "A1" or "ghost A", was periodically keyed in, and the pattern of flashing on the display could be used to identify the chain. The operator initially tuned in their receiver to see a stream of pulses on the display, sometimes including those of other chains which were nearby in frequency. They would then tune a local oscillator that triggered

20600-448: The end of the war, there were 72 operational LORAN stations and as many as 75,000 receivers. In 1958 the operation of the LORAN system was handed over to the United States Coast Guard , which renamed the system "Loran-A", the lower-case name being introduced at that time. There are two ways to implement the timing measurements needed for a hyperbolic navigation system, pulse timing systems like Gee and LORAN, and phase-timing systems like

20800-464: The end of the war. The U.S. Navy had followed in the footsteps of the navies of Great Britain and Germany which favored concentrated groups of battleships as their main offensive naval weapons. The development of the aircraft carrier and its devastating use by the Japanese against the U.S. at Pearl Harbor, however, shifted U.S. thinking. The Pearl Harbor attack destroyed or took out of action a significant number of U.S. Navy battleships. This placed much of

21000-415: The end. In every period, one of the two secondaries would respond, alternating their "B" and "C" signals. The resulting pattern was "ABD…ACD…ABD…" A wide-band receiver was used to tune in chain and the output sent to the operator's oscilloscope . As the chains were closely spaced in frequency to allow them to be received by a single tuner, this sometimes resulted in the signals from several chains appearing on

21200-526: The face of the expiration of budget relief offered by the Bipartisan Budget Act of 2013 and CNO Jonathan Greenert said that a ten ship carrier fleet would not be able to sustainably support military requirements. The British First Sea Lord George Zambellas said that the USN had switched from "outcome-led to resource-led" planning. One significant change in U.S. policymaking that is having

21400-654: The first three commands being led by four-star admirals. The United States First Fleet existed after World War II from 1947, but it was redesignated the Third Fleet in early 1973. The Second Fleet was deactivated in September 2011 but reestablished in August 2018 amid heightened tensions with Russia. It is headquartered in Norfolk, Virginia, with responsibility over the East Coast and North Atlantic. In early 2008,

21600-566: The first three were brought into service: USS  United States , USS  Constellation , and USS  Constitution . Due to his strong posture on having a strong standing Navy during this period, John Adams is "often called the father of the American Navy". In 1798–99 the Navy was involved in an undeclared Quasi-War with France. From 1801 to 1805, in the First Barbary War , the U.S. Navy defended U.S. ships from

21800-424: The first time at the Battle of Hampton Roads in 1862, which pitted USS  Monitor against CSS  Virginia . For two decades after the war, however, the U.S. Navy's fleet was neglected and became technologically obsolete . A modernization program beginning in the 1880s when the first steel-hulled warships stimulated the American steel industry, and "the new steel navy" was born. This rapid expansion of

22000-491: The first uniform regulations for officers were issued in 1802 on the formation of the Navy Department. The predominant colors of U.S. Navy uniforms are navy blue and white. U.S. Navy uniforms were based on Royal Navy uniforms of the time and have tended to follow that template. Navy officers serve either as a line officer or as a staff corps officer . Line officers wear an embroidered gold star above their rank of

22200-456: The fleet has shrunk and that in the face of declining budgets in the future, the U.S. Navy must rely even more on international partnerships. In its 2013 budget request, the navy focused on retaining all eleven big deck carriers, at the expense of cutting numbers of smaller ships and delaying the SSBN replacement. By the next year the USN found itself unable to maintain eleven aircraft carriers in

22400-705: The fleet, and making naval technological improvements. During the Mexican–American War the U.S. Navy blockaded Mexican ports, capturing or burning the Mexican fleet in the Gulf of California and capturing all major cities in Baja California peninsula. In 1846–1848 the Navy successfully used the Pacific Squadron under Commodore Robert F. Stockton and its marines and blue-jackets to facilitate

22600-509: The ground stations. During this time he demanded that an airborne version of the receivers be made, and should be interchangeable with Gee. The resulting system emerged as LORAN , for LOng RAnge Navigation, and the first chain of two stations went live in June 1942. LORAN became LORAN-A when the design of its replacement started, this was initially the LORAN-B concept, but eventually replaced by

22800-588: The hands of the Barbary pirates from Algiers , the United States Congress passed the Naval Act of 1794 for the construction of six heavy frigates , the first ships of the Navy. The United States Navy played a major role in the American Civil War by blockading the Confederacy and seizing control of its rivers. It played the central role in the World War II defeat of Imperial Japan . The United States Navy emerged from World War II as

23000-411: The inherent disadvantage that the signal could only vary by as much as 360 degrees, and that pattern repeated in a circle around the stations. That meant there were a large number of locations that met any particular phase measurement, a problem known as "phase ambiguity". Whereas Gee and LORAN fixed you in one of two locations, Decca fixed you to one in hundreds. As the ambiguous regions radiated away from

23200-531: The initial suit, but the judgement was overturned on appeal when the Navy claimed "wartime expediency". When Loran-C became widespread, the United States Air Force once again became interested in using it as a guidance system. They proposed a new system layered on top of Loran-C to provide even higher accuracy, using the Loran-C fix as the coarse guidance signal in much the same way that Loran-C extracted coarse location from pulse timing to remove

23400-445: The late 1950s offered accuracy within a few miles, which was enough to determine the lane. Experiments on the concept continued throughout the 1950s and 60s, in parallel with Decca's development of their almost identical DELRAC system. It was not until the 1960s, when ice-breaking ballistic submarines became a main deterrent force, that there was a pressing need for such a system. The US Navy authorized full deployment in 1968, reaching

23600-443: The late 1970s, especially in the early 1980s, and the earlier LORAN system was discontinued in favor of installing more Loran-C stations around the world. Loran-C became one of the most common and widely-used navigation systems for large areas of North America, Europe, Japan and the entire Atlantic and Pacific areas. The Soviet Union operated a nearly identical system, CHAYKA . The introduction of civilian satellite navigation in

23800-519: The market. This made Loran-A popular in spite of being less accurate and fairly difficult to operate. By the early 1970s the introduction of integrated circuits combining a complete radio receiver began to greatly reduce the complexity of Loran-A measurements, and fully automated units the size of a stereo receiver became common. For those users requiring higher accuracy, Decca had considerable success with their Decca Navigator system, and produced units that combined both receivers, using Loran to eliminate

24000-475: The master in the center, allowing a receiver to pick the signals from two secondaries that are currently as close to right angles as possible given their current location. Modern systems, which know the locations of all the broadcasters, can automate which stations to pick. In the case of LORAN, one station remains constant in each application of the principle, the primary , being paired up separately with two other secondary stations. Given two secondary stations,

24200-610: The middle of the baseline, but also if they are located 200 km from both stations, and 300 km, and so forth. So in this case the receiver cannot determine their exact location, only that their location lies somewhere along a line perpendicular to the baseline. In the second example the receivers determined the timing to be 0.25 and 0.75 ms, so this would produce a measured delay of 0.5 ms. There are many locations that can produce this difference - 0.25 and 0.75 ms, but also 0.3 and 0.8 ms, 0.5 and 1 ms, etc. If all of these possible locations are plotted, they form

24400-468: The mission of the U.S. Armed Forces is "to be prepared to conduct prompt and sustained combat operations in support of the national interest." The Navy's five enduring functions are: sea control , power projection , deterrence , maritime security , and sealift . It follows then as certain as that night succeeds the day, that without a decisive naval force we can do nothing definitive, and with it, everything honorable and glorious. Would to Heaven we had

24600-529: The most common ground since aircrews are guided in their use of aircraft by standard procedures outlined in a series of publications known as NATOPS manuals. The United States Coast Guard , in its peacetime role with the Department of Homeland Security , fulfills its law enforcement and rescue role in the maritime environment. It provides Law Enforcement Detachments (LEDETs) to Navy vessels, where they perform arrests and other law enforcement duties during naval boarding and interdiction missions. In times of war,

24800-476: The most important is the "warfare qualification", which denotes a journeyman level of capability in Surface Warfare, Aviation Warfare, Information Dominance Warfare, Naval Aircrew, Special Warfare, Seabee Warfare, Submarine Warfare or Expeditionary Warfare. Many qualifications are denoted on a sailor's uniform with U.S. Navy badges and insignia . The uniforms of the U.S. Navy have evolved gradually since

25000-597: The most powerful navy in the world. The modern United States Navy maintains a sizable global presence, deploying in strength in such areas as the Western Pacific , the Mediterranean , and the Indian Ocean. It is a blue-water navy with the ability to project force onto the littoral regions of the world, engage in forward deployments during peacetime and rapidly respond to regional crises, making it

25200-495: The naval service dress uniform while staff corps officers and commissioned warrant officers wear unique designator insignias that denotes their occupational specialty. Warrant and chief warrant officer ranks are held by technical specialists who direct specific activities essential to the proper operation of the ship, which also require commissioned officer authority. Navy warrant officers serve in 30 specialties covering five categories. Warrant officers should not be confused with

25400-417: The need to re-synchronize. Much development was needed before these became practical, but these issues were mostly solved by the 1960s. This left one other problem; phase comparison systems of this sort are ambiguous and need some other system to resolve which lane they are within. This was also in the process of being solved through the development of inertial navigation systems (INS). Even early models from

25600-480: The newly-formed United States Air Force, known as Operation Beetle. Beetle was located in the far north, on the Canada-Alaska border, and used new guy-stayed 625 feet (191 m) steel towers, replacing the earlier system's balloon-lofted cable antennas. The system became operational in 1948 and ran for two years until February 1950. Unfortunately, the stations proved poorly sited, as the radio transmission over

25800-719: The notion of prevention of war to the same philosophical level as the conduct of war. The strategy was presented by the Chief of Naval Operations , the Commandant of the Marine Corps , and Commandant of the Coast Guard at the International Sea Power Symposium in Newport, Rhode Island on 17 October 2007. The strategy recognized the economic links of the global system and how any disruption due to regional crises (man-made or natural) can adversely impact

26000-410: The number two official in the Navy Department during World War I, appreciated the Navy and gave it strong support. In return, senior leaders were eager for innovation and experimented with new technologies, such as magnetic torpedoes, and developed a strategy called War Plan Orange for victory in the Pacific in a hypothetical war with Japan that would eventually become reality. The U.S. Navy grew into

26200-539: The ocean-going schooner USS Hannah to interdict British merchantmen and reported the captures to the Congress. On 13 October 1775, the Continental Congress authorized the purchase of two vessels to be armed for a cruise against British merchantmen; this resolution created the Continental Navy and is considered the first establishment of the U.S. Navy. The Continental Navy achieved mixed results; it

26400-427: The operational environment, as an expeditionary force specializing in amphibious operations, Marines often embark on Navy ships to conduct operations from beyond territorial waters. Marine units deploying as part of a Marine Air-Ground Task Force (MAGTF) operate under the command of the existing Marine chain of command. Although Marine units routinely operate from amphibious assault ships, the relationship has evolved over

26600-485: The operator could gain additional timing accuracy by lining up the individual waves within the pulse, like Decca. This could either be used to greatly increase the accuracy of LORAN, or alternately, offer similar accuracy using much lower carrier frequencies, and thus greatly extend the effective range. This would require the transmitter stations to be synchronized both in time and phase, but much of this problem had already been solved by Decca engineers. The long-range option

26800-405: The operator to pick the pair of signals on the display that were sent from stations as close to right angles to the receiver as possible, further improving accuracy. Maximum accuracy was normally quoted as 200 yards, although that was subject to operational errors. In addition to greater accuracy and ease of use, Decca was also more suitable for use over land. Delays due to refraction can have

27000-412: The order of 100 yards, while adding the correction contour adjustments reduced this to the order of ten yards. It was at this moment that the United States Air Force, having taken over these efforts while moving from the United States Army Air Forces , dropped their interest in the project. Although the reasons are not well recorded, it appears the idea of a fully automated bombing system using radio aids

27200-457: The order of a few miles over distances on the order of 1,250 miles (2,010 km), at least at night when signals of this frequency range were able to skip off the ionosphere . Rapid development followed, and a system covering the western Atlantic was operational in 1943. Additional stations followed, first covering the European side of the Atlantic, and then a large expansion in the Pacific. By

27400-406: The original signal was sent. In theory, one could synchronize an accurate clock to the signal before leaving port, and then use that to compare the timing of the signal during the voyage. However, in the 1940s no suitable system was available that could hold an accurate signal over the time span of an operational mission. Instead, radio navigation systems adopted the multilateration concept which

27600-399: The oscilloscope's trace so that it matched the clock at the primary station (which could, and did, change over time). Next, they would use a variable delay that was added to the local oscillators signal to move the entire display back or forth so one of the "A" pulses was at the very left side of the 'scope (the action is identical to the "horizontal hold" dial on an analog television). Finally,

27800-451: The other organizations, playing a coordinating role. In 1834, the United States Marine Corps came under the Department of the Navy. Historically, the Navy has had a unique relationship with the USMC, partly because they both specialize in seaborne operations. Together the Navy and Marine Corps form the Department of the Navy and report to the Secretary of the Navy. However, the Marine Corps

28000-409: The other. If one draws circles of 300 and 450 km radius around the two stations on a chart, the circles will intersect at two points. With any additional source of navigation information, one of these two intersections can be eliminated as a possibility, and thus reveal their exact location, or "fix". There is a serious practical problem with this approach - in order to measure the time it took for

28200-422: The output of a local clock that locked to the master carrier using a phase-locked loop . This retained the phase of the master signal long enough for the secondary signal to arrive. Gating on the secondary signal was then compared to this master signal in a phase detector , and a varying voltage was produced depending on the difference in phase. This voltage represented the fine-positioning measurement. The system

28400-477: The output shifted back and forth on the face of the oscilloscope. By this time the team had become much more familiar with the British Gee system, and were aware of their related work on "strobes", a time base generator that produced well-positioned "pips" on the display that could be used for accurate measurement. This meant that inaccuracy of the positioning on the display had no effect: any inaccuracy in

28600-566: The phase measurements to place the receiver accurately within the cell. Numerous efforts were made to provide some sort of secondary low-accuracy system that could be used with a phase-comparison system like Decca in order to resolve the ambiguity. Among the many methods was a directional broadcast system known as POPI , and a variety of systems combining pulse-timing for low-accuracy navigation and then using phase-comparison for fine adjustment. Decca themselves had set aside one frequency, "9f", for testing this combined-signal concept, but did not have

28800-406: The phase of two signals. This system is easy to use even at very low frequencies. However, its signal is ambiguous over the distance of a wavelength, meaning there are hundreds of locations that will return the same signal. Decca referred to these ambiguous locations as cells . This demands some other navigation method to be used in conjunction to pick which cell the receiver is within, and then using

29000-507: The phases of continuous signals instead of the timing of their pulses. This was more accurate, as the phase of a pair of signals could be measured to within a few degrees, four degrees in the case of Decca. This greatly improved inherent accuracy allowed Decca to use much longer wavelengths than Gee or LORAN while still offering the same level of accuracy. The use of longer wavelengths gave better propagation than either Gee or LORAN, although ranges were generally limited to around 500 miles for

29200-436: The position of the signal was also in the strobe, so the two remained aligned. The Project 3 team met with the Gee team in 1941, and immediately adopted this solution. This meeting also revealed that Project 3 and Gee called for almost identical systems, with similar performance, range and accuracy, but Gee had already completed basic development and was entering into initial production, making Project 3 superfluous. In response,

29400-671: The potential security advantages of Loran are worthy not only of keeping the system operational, but upgrading it and adding new stations. This is part of the wider Eurofix system which combines GPS, Galileo and nine Loran stations into a single integrated system. In 2014, Norway and France both announced that all of their remaining transmitters, which make up a significant part of the Eurofix system, would be shut down on 31 December 2015. The two remaining transmitters in Europe ( Anthorn , UK and Sylt , Germany) would no longer be able to sustain

29600-426: The pulses to be received over very long ranges. This produced considerably more complex received signals than with Gee's line-of-sight system, and was more difficult to interpret. With that exception, however, the two systems were very similar in concept, and differed largely in frequency selections and the details of the pulse timing. Robert J. Dippy , inventor of Gee, moved to the US in mid-1942 to help with details of

29800-454: The range of the system. However, the accuracy of the fix is a function of the wavelength of the signal, which increases at lower frequencies - in other words, using a lower frequency would necessarily lower the accuracy of the system. Hoping for the best, early experiments with "LF Loran" instead proved that accuracy was far worse than predicted, and efforts along these lines were dropped. Several halting low-frequency efforts followed, including

30000-421: The range to the target. With very slight modification, the same display could be used to time the difference between two arbitrary signals. For navigational use, any number of identifying characteristics could be used to differentiate the primary from secondary signals. In this case, the portable receiver triggered its trace when it received the primary signal. As the signals from secondary arrived they would cause

30200-446: The same time on different frequencies. Receivers would select the set of stations that were most suitable for their given location, and then wait for the signals for those stations to appear during the 10 second chain. Calculation of the fix then proceeded in precisely the same fashion as Decca, although the much lower operating frequency led to much less accuracy. Omega's charts quote accuracies of 2 to 4 nautical miles. CHAYKA

30400-441: The same time so the signals can be compared. This reveals a difference in time, corresponding to a relative distance closer to one station or the other. Plotting all the locations where this time difference may occur produces a hyperbolic line on a chart. To take a "fix", a second station pair is also turned in to produce a second such curve. The two curves will normally intersect at two locations, so some other navigation system or

30600-404: The same time, or continual signals that are identical in phase . A receiver located at the midpoint between the two stations will receive the signals at the same time or have identical phase, but at any other location the signal from the closer station will be received first or have a different phase. Determining the location of a receiver requires that the two synchronized stations be tuned in at

30800-426: The satellite coordinates be known as a function of time (included in the broadcast messages). Item (2) enables satnav systems to provide timing as well as position information, but requires a more complex solution algorithm. However, these are technical differences from earth-fixed hyperbolic systems, but not fundamental differences. United States Navy 13 October 1775 (249 years, 1 month) (as

31000-447: The satellite navigation era, until GPS finally led to its shutdown on 8 February 2010. In basic operation, measurement was a two-step process. The signals would first be tuned in and lined up on the screen in a fashion similar to Gee, with the position of the blips being used to produce a rough estimate of the location. This measurement was accurate enough to place the vehicle within a specific lane. The operator would then greatly magnify

31200-440: The secondaries could trigger when they heard the signal from the primary, but for a global system, the stations might not be visible to each other, especially when the atmosphere was not cooperative. The solution to this was introduced in 1955 in the form of the caesium atomic clock . These offered enough accuracy that they could be synchronized at their factory, shipped to the transmitter locations, and left running for years without

31400-663: The senior command meant that naval forces were not contributed until late 1917. Battleship Division Nine was dispatched to Britain and served as the Sixth Battle Squadron of the British Grand Fleet. Its presence allowed the British to decommission some older ships and reuse the crews on smaller vessels. Destroyers and U.S. Naval Air Force units like the Northern Bombing Group contributed to the anti-submarine operations. The strength of

31600-1052: The shore establishment, as of April 2011 , are the Naval Education and Training Command , the Navy Installations Command , the Naval Meteorology and Oceanography Command , the Naval Information Warfare Systems Command , the Naval Facilities Engineering Command , the Naval Supply Systems Command , the Naval Air Systems Command , the Naval Sea Systems Command , the Bureau of Medicine and Surgery ,

31800-407: The signal crossed caused predictable delays that could be measured and then factored into navigation solutions. This led to a series of correction contours that could be added to the received signal to adjust for these concerns, and these were printed on the Cytac charts. Using prominent features on dams as target points, a series of tests demonstrated that the uncorrected signals provided accuracy on

32000-532: The signal timings to select chains, identify secondaries, and reject signals bounced off the ionosphere. LORAN-C chains were organized into the Master station, M, and up to five Secondary stations, V, W, X, Y, Z. All were broadcast at 100 kHz, a much lower frequency than earlier systems. The result was a signal that offered a daytime ground wave range of 2,250 miles, nighttime ground wave of 1,650 miles and skywaves out to 3,000 miles. Timing accuracy

32200-411: The signals to reach the receiver, the receiver must know the precise time that the signal was originally sent. This is not possible in the case of uncooperative signal sources (like enemy artillery) and until the 2000s, widespread clock distribution was an unsolved problem until the widespread introduction of inexpensive GPS receivers. In the 1930s, such precise time measurements simply weren't possible;

32400-406: The signals, which meant that Loran-C was used primarily by militaries after it was introduced in 1957. By the 1970s, the cost, weight and size of electronics needed to implement Loran-C had been dramatically reduced because of the introduction of solid-state electronics and, from the mid-1970s, early microcontrollers to process the signal. Low-cost and easy-to-use Loran-C units became common from

32600-417: The speed of the trace across the display would be tuned so the D pulse was just visible on the right. The distance of the B or C pulse from the A pulse could now be measured with an attached scale. The resulting delays could then be looked up on a navigational chart. The display was relatively small, which limited resolution, and thus the determination of the delay. A measurement accuracy of 1 microsecond

32800-414: The stations and had a finite width, these became known as "lanes". Decca solved this problem through the use of an odometer -like display known as "decometers". Prior to leaving on a trip, the navigator would set the decometer's lane counter to their known position. As the craft moved the dial's hand would rotate, and increment or decrement the counter when it passed zero. The combination of this number and

33000-588: The successful bombardment and capture of the city. This successful landing and capture of Veracruz opened the way for the capture of Mexico City and the end of the war. The U.S. Navy established itself as a player in United States foreign policy through the actions of Commodore Matthew C. Perry in Japan, which resulted in the Convention of Kanagawa in 1854. Naval power played a significant role during

33200-454: The system as well, using it for navigation on the great circle route between North America and Europe. However, inertial platforms ultimately became more common in this role. In 1969, Decca sued the United States Navy for patent infringement, producing ample documentation of their work on the basic concept as early as 1944, along with the "missing" 9f frequency at 98 kHz that had been set aside for experiments using this system. Decca won

33400-508: The system even easier to use. As each primary and secondary signal was sent at a different frequency, any number of delays could be measured at the same time; in practice, a single primary and three secondaries were used to produce three outputs. As each signal was sent on a different frequency, all three, known as "green", "red" and "purple", were simultaneously decoded and displayed on three decometers. The secondaries were physically distributed at 120 degree angles from each other, allowing

33600-492: The system to be operated more rapidly than the original LORAN's multi-minute measurement. It was also operated in "chains" of linked stations, allowing a fix to be made by simultaneously comparing two secondaries to a single master. The downside of this approach was that the required electronic equipment, built using 1950s-era tube technology, was very large. Looking for companies with knowledge of seaborne, multi-channel phase-comparison electronics led, ironically, to Decca, who built

33800-514: The time difference (TD) between the primary and first secondary identifies one curve, and the time difference between the primary and second secondary identifies another curve, the intersections of which will determine a geographic point in relation to the position of the three stations. These curves are referred to as TD lines . In practice, LORAN is implemented in integrated regional arrays , or chains , consisting of one primary station and at least two (but often more) secondary stations, with

34000-401: The time-of-flight of the signals. In comparison to angle measurements, these remain fairly steady over time, and most of the effects that change these values are fixed objects like rivers and lakes that can be accounted for on charts. Timing systems can reveal the absolute distance to an object, as is the case in radar . The problem in the navigational case is that the receiver has to know when

34200-418: The timing of the signals would change. For instance, if they time the signals at 0.25 and 0.75 ms, they are 75 km from the closer station and 225 from the further. If the receiver moves to the side of the baseline, the delay from both stations will grow. At some point, for instance, they will measure a delay of 1 and 1.5 ms, which implies the receiver is 300 km from one station and 450 from

34400-482: The treaty. The New Deal used Public Works Administration funds to build warships, such as USS  Yorktown  (CV-5) and USS  Enterprise  (CV-6) . By 1936, with the completion of USS  Wasp  (CV-7) , the U.S. Navy possessed a carrier fleet of 165,000 tonnes displacement , although this figure was nominally recorded as 135,000 tonnes to comply with treaty limitations. Franklin Roosevelt ,

34600-412: The two copies of the signal when the same pulses were being compared. None of this was trivial; using the era's tube-based electronics, the experimental CYCLAN system filled much of a semi-trailer . CYCLAN proved highly successful, so much so that it became increasingly clear that the problems that led the engineers to use two frequencies were simply not as bad as expected. It appeared that a system using

34800-485: The two signals, that implies that the receiver is somewhere along a line equidistant between the two. If the signal from one is received exactly 100 μs after, then the receiver is 30 kilometres (19 mi) closer to one station than the other. Plotting all the locations where one station is 30 km closer than the other produces a curved line. Taking a fix is accomplished by making two such measurements with different pairs of stations, and then looking up both curves on

35000-404: The very long-range LORAN-C starting in 1957. LORAN eventually selected 1.950 MHz as its primary operating frequency. 7.5 MHz was selected for daytime use as an additional channel, but never used operationally. In comparison to Gee's 450 miles (720 km) range through air, LORAN had a range of about 1,500 miles (2,400 km) over water, and 600 miles (970 km) over land. Operation

35200-460: The widespread availability of Loran-A charts, many Loran-C receivers included a system for converting coordinates between A and C units. One of the reasons for Loran-C's opening to the public was the move from Loran to new forms of navigation, including inertial navigation systems , Transit and OMEGA , meant that the security of Loran was no longer as stringent as it was as a primary form of navigation. As these newer systems gave way to GPS through

35400-604: The years much as the Commander of the Carrier Air Group/Wing (CAG) does not work for the carrier commanding officer, but coordinates with the ship's CO and staff. Some Marine aviation squadrons, usually fixed-wing assigned to carrier air wings train and operate alongside Navy squadrons; they fly similar missions and often fly sorties together under the cognizance of the CAG. Aviation is where the Navy and Marines share

35600-592: Was UK's Gee , first used experimentally by RAF Bomber Command in 1941. Gee was used both for bombing over Germany as well as navigation in the area of the UK, especially for landing at night. Several Gee chains were built in the UK, and after the war this expanded for four chains in the UK, two in France, and one in northern Germany. For a period following the formation of the International Civil Aviation Organization in 1946, Gee

35800-588: Was a major participant in the Korean and Vietnam Wars , blockaded Cuba during the Cuban Missile Crisis , and, through the use of ballistic missile submarines , became an important aspect of the United States' nuclear strategic deterrence policy. The U.S. Navy conducted various combat operations in the Persian Gulf against Iran in 1987 and 1988, most notably Operation Praying Mantis . The Navy

36000-428: Was abandoned. CYCLAN operated by sending the same LF LORAN-like signals on two frequencies, LF LORAN's 180 kHz and again on 200 kHz. The associated equipment would look for a rising amplitude that indicated the start of the signal pulse, and then use sampling gates to extract the carrier phase. Using two receivers solved the problem of mis-aligning the pulses, because the phases would only align properly between

36200-472: Was considered as the basis for a worldwide standard for navigation, but the VHF omnidirectional range (VOR) system was selected instead, and the last Gee chain was eventually shut down in 1970. Gee signals from a given chain were all sent on a single frequency. The primary station sent two signals, the "A" signal that marked the beginning of a timing period, and the "D" signal which was essentially two "A"s to mark

36400-465: Was estimated at 0.15 microseconds, offering accuracies on the order of 50 to 100 meters. In real-world use, the Coast Guard quoted absolute accuracy of 0.25 nautical miles, or better. One of the last hyperbolic navigation systems to enter operational use was one of the earliest to be developed; Omega traces its history to work by John Alvin Pierce in the 1940s, working on the same basic idea as

36600-493: Was extensively involved in Operation Urgent Fury , Operation Desert Shield , Operation Desert Storm , Operation Deliberate Force , Operation Allied Force , Operation Desert Fox and Operation Southern Watch . The U.S. Navy has also been involved in search and rescue/search and salvage operations, sometimes in conjunction with vessels of other countries as well as with U.S. Coast Guard ships. Two examples are

36800-714: Was faced with a two-front war on the seas. It achieved notable acclaim in the Pacific Theater , where it was instrumental to the Allies' successful " island hopping " campaign. The U.S. Navy participated in many significant battles, including the Battle of the Coral Sea , the Battle of Midway , the Solomon Islands Campaign , the Battle of the Philippine Sea , the Battle of Leyte Gulf , and

37000-411: Was generally similar to Gee, but only one of the secondary signals was displayed at a time. A fix required the operator to measure one delay, then the other, and then look up the resulting delays on the charts. This was a time-consuming process that could take several minutes, during which time the vehicle was moving. The accuracy was quoted as 1% of range. LORAN used two methods to identify a chain. One

37200-407: Was generally successful during testing through 1953, but there were concerns raised about the signal power at long range and the possibility of jamming. This led to further modifications of the basic signal. The first was to broadcast a series of pulses instead of just one, broadcasting more energy during a given time and improving the ability of the receivers to tune in a useful signal. They also added

37400-523: Was largely redundant by 2000, it has not universally disappeared as of 2014 due to a number of concerns. One is that the GPS system can be jammed through a variety of means. Although the same is true of Loran-C, the transmitters are close-at-hand and can be adjusted if necessary. More importantly, there are effects that might cause the GPS system to become unusable over wide areas, notably space weather events and potential EMP events. Loran, located entirely under

37600-423: Was needed. Common methods included transmitting from the secondary only at certain times, using different frequencies, adjusting the envelope of the burst of signal, or broadcasting several bursts in a particular pattern. A set of stations, primary and secondaries, was known as a "chain". Similar methods are used to identify chains in the case where more than one chain may be received in a given location. Meint Harms

37800-452: Was no longer considered possible. The AAF had been involved in missions covering about 1000 km (the distance from London to Berlin) and the Cytac system would work well at these ranges, but as the mission changed to trans-polar missions of 5,000 km or more, even Cytac did not offer the range and accuracy needed. They turned their attention to the use of inertial platforms and Doppler radar systems, cancelling work on Cytac as well as

38000-671: Was not until 1921 US naval aviation truly commenced. During World War I , the U.S. Navy spent much of its resources protecting and shipping hundreds of thousands of soldiers and marines of the American Expeditionary Force and war supplies across the Atlantic in U-boat infested waters with the Cruiser and Transport Force . It also concentrated on laying the North Sea Mine Barrage . Hesitation by

38200-402: Was of considerable interest to the Coast Guard, who set up an experimental system known as LF LORAN in 1945. This operated at much lower frequencies than the original LORAN, at 180 kHz, and required very long balloon-borne antennas. Testing was carried out throughout the year, including several long-distance flights as far as Brazil . The experimental system was then sent to Canada where it

38400-418: Was of the essence. Several versions of Decca were introduced for this role, notably DECTRA and DELRAC, but these did not see widespread use. LORAN-A was designed to be quickly built on the basis of Gee, and selected its operating frequency based on the combination of the need for long over-water range and a selected minimum accuracy. Using much lower frequencies, in the kHz instead of MHz, would greatly extend

38600-511: Was quoted, which resulted in an accuracy of the determination of the correct hyperbolic to about 150 meters, and when two such measurements were combined the resulting fix accuracy was around 210 m. At longer ranges, 350 miles for example, the error ellipse was about 6 miles by 1 mile. The maximum range was about 450 miles, although several long-range fixes were made under unusual circumstances. The US had also considered hyperbolic navigation as early as 1940, and started

38800-403: Was successful in a number of engagements and raided many British merchant vessels, but it lost twenty-four of its vessels and at one point was reduced to two in active service. In August 1785, after the Revolutionary War had drawn to a close, Congress had sold Alliance , the last ship remaining in the Continental Navy due to a lack of funds to maintain the ship or support a navy. In 1972,

39000-493: Was the World War II -era Gee , introduced by the Royal Air Force for use by RAF Bomber Command . This was followed by the Decca Navigator System in 1944 by the Royal Navy , along with LORAN by the US Navy for long-range navigation at sea. Post war examples including the well-known US Coast Guard Loran-C , the international Omega system, and the Soviet Alpha and CHAYKA . All of these systems saw use until their wholesale replacement by satellite navigation systems like

39200-538: Was the first to have attempted the construction of a hyperbolic navigation systems, starting with musings on the topic in 1931 as part of his master's examination at Seefahrtschule Lübeck (Navigation College). After taking the position of Professor for Mathematics, Physics and Navigation at the Kaisertor in Lübeck, Harms tried to demonstrate hyperbolic navigation making use of simple transmitters and receivers. On 18 February 1932 he received Reichspatent-Nr. 546000 for his invention. The first operational hyperbolic navigation

39400-437: Was the operational frequency, with four "channels", as in Gee. The second was the rate at which the pulses were repeated, with "high", "low" and "slow" rates. This allowed for up to 12 chains in any given area. Additionally, the originally steady repetition of the pulses was later modified to create another eight unique patterns, allowing a total of 96 station pairs. Any given chain could use one or more pairs of stations, demanding

39600-483: Was used briefly but it was found that Loran-D met the same requirements but had the added advantage of being a standard Loran-C signal as well. Although MUTNS was unrelated to the Loran systems, it was sometimes referred to as Loran-F . In spite of its many advantages, the high cost of implementing a Loran-C receiver made it uneconomical for many users. Additionally, as military users upgraded from Loran-A to Loran-C, large numbers of surplus Loran-A receivers were dumped on

39800-516: Was used during Operation Muskox in the Arctic. Accuracy was found to be 150 feet (46 m) at 750 miles (1,210 km), a significant advance over LORAN. With the ending of Muskox, it was decided to keep the system running under what became known as "Operation Musk Calf", run by a group consisting of the United States Air Force , Royal Canadian Air Force , Royal Canadian Navy and the UK Royal Corps of Signals . The system ran until September 1947. This led to another major test series, this time by

40000-470: Was used only experimentally during war-games in the 1960s from a transmitter set in the UK. The system was also used in a limited fashion during the Vietnam War , combined with the Pave Spot laser designator system, a combination known as Pave Nail. Using mobile transmitters, the AN/ARN-92 LORAN navigation receiver could achieve accuracy on the order of 60 feet (18 m), which the Spot laser improved to about 20 feet (6.1 m). The SIM concept later became

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